草原化荒漠植被草本层片植物对人工施加氮素的响应

摘要/Abstract

摘要： 水分是干旱区生态过程的第一非生物限制因子,土壤氮由于直接影响着生物生产力和土壤生态过程而被认为是仅次于水分的限制因子。利用人工施加氮肥的控制试验研究了荒漠植被草本层片植物在多度、物种丰富度、高生长以及地上部分生物量等群落学特征对不同施肥处理的响应。结果表明,在施肥量分别为12.5、25、50 g·m-2时,样方植物多度和物种丰富度在施肥当年和第二年较对照均有不同程度的降低,且施肥量越高,降低越明显,这一结果支持来自典型草地和森林植被生物多样性对氮素增加或氮降沉增加响应的结论,即氮素的增加会使生物多样性减少。地上部分生物量对施氮肥的响应在施肥当年(年降水量为多年平均值的1.4倍)和第二年(年降水量为多年平均值的0.7倍)表现出相反的规律,即施肥当年随着施肥量的增加生物量显著增加,而在第二年则显著减小,说明水肥耦合同样有利于荒漠生态系统生物生产力的提高。氮素对植物高生长的影响不明显,各施肥梯度与对照相比均无显著性差异(P>0.05),这可能主要取决于荒漠草本植物本身固有的生物学特性。

关键词: 荒漠化草原, 草本层片, 氮肥, 物种丰富度, 地上部分生物量

Abstract: Water content is the first abiotic limiting factor of the ecological process in desert region, while soil nitrogen is usually considered as the secondary limiting factor because of its direct influence on vegetation productivity and soil ecological process. The response of plant abundance, species richness, species height and aboveground biomass of desert herbaceous vegetation to nitrogen fertilizer amended artificially was investigated in the paper. The result indicated that both plant abundance and species richness decreased in the year of nitrogen fertilizer treatment and the second year under 12.5, 25, 50 g·m-2 fertilization levels compared to no nitrogen fertilizer amended treatment. The higher the gradient of fertilizer levels, the more obvious plant abundance and species richness decreased, which supported the conclusion derived from the response of characteristic grassland and forest vegetation to nitrogen increase or nitrogen deposition that biodiversity would reduce with the increase of nitrogen. However, aboveground biomass showed the opposite response to nitrogen fertilizer in the first year (annual precipitation was 1.4 times over the average) and the second year (annual precipitation was 0.7 times over the average), and aboveground biomass increased with the gradient of fertilizer levels in the first year and decreased in the second year significantly, which showed that coupling of water and fertilizer similarly is beneficial to the improvement of desert ecosystem productivity. Vegetation height showed no significant difference under the gradient of nitrogen fertilizer levels (P>0.05), which possibly was determined by the inherent biological characteristics of desert herbaceous vegetation.

Key words: desert grassland, herb layer, nitrogen fertilizer, species richness, aboveground biomass

中图分类号:

Q945.3

苏洁琼;李新荣;李小军;贺郝钰;贾荣亮;高永平. 草原化荒漠植被草本层片植物对人工施加氮素的响应[J]. 中国沙漠, 2010, 30(6): 1336-1340.

SU Jie-qiong;LI Xin-rong;LI Xiao-jun;HE Hao-yu;JIA Rong-liang;GAO Yong-ping. Response of Vegetation Herb Layer to Nitrogen Fertilizer in Steppe Desert[J]. JOURNAL OF DESERT RESEARCH, 2010, 30(6): 1336-1340.

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